You can't connect to Lync Online, or certain features don't work, because an on-premises firewall blocks the connection

Additionally, make sure that the 65.54.54.0/24 IP range is open in your firewall. This range covers the Office Online server from which PowerPoint presentations are streamed.

Check the integrity of the PowerPoint presentation

If a static image isn't displayed correctly, try to reproduce the issue by using the same .ppt file that contains the image. Then, try to reproduce the issue by using a different .ppt file that contains the same image.

Be aware that some content (video, multimedia, and so on) will be removed from the deck during the upload process.

Verify that the PowerPoint presentation that you want to upload isn't open anywhere else on the system.

Verify that there are no open dialog boxes in PowerPoint. (For example, a dialog box appears when you click File and then click Open.)

Check local permissions and settings

Verify that you have the correct certificates in Certificate Manager. To do this, follow these steps:

Open Certificate Manager. To do this, click Start, click Run, type certmgr.msc, and then click OK.

Expand Personal, and then expand Certificates.

Click the heading for the Issued By column to sort the column, and then look for a certificate that's issued by Communications Server.

Verify that the certificate is present and isn't expired.

If the certificate is expired, right-click the certificate, point to All Tasks, and then click Delete.

Try to sign in to Lync Online. This action will download a new certificate if sign-in is successful.

Verify that you have the appropriate permissions to save to your target destination.

Verify that the user has permissions to save content. Have a presenter open the content bin (or attachments, if the file is an attachment), click the right arrow (or right-click), and then click Make Available to. Make sure that Make Available to is set to the role of the person who is trying to save the file.

If you save to a network location, verify that you have Read/Write permissions to the network share.

If you can't save content in the XPS format only, check the XPS print queue. To do this, click Start, click Devices and Printers, open the Microsoft XPS Document Writer, and then delete all pending jobs that seem to be stuck.

For the second error message, if Lync Online can't send you a connection URL, you see the following entry in the Lync 2013 log files:

<diagHeader>54006;reason="A resource was unable to be uploaded to the Web Conferencing Server";ClientType=Lync;Build=15.0.4128.1019;ContentMCU="sip:DeanH@trtcmd.com;gruu;opaque=app:conf:data-conf:id:2TTC0TM5";ConferenceUri="sip:deanh@trtcmd.com;gruu;opaque=app:conf:focus:id:2TTC0TM5";HrReason="0x80F10248";PackedSize="2489286";UnpackedSize="2490375";ServerReason="4";ServerReasonString="UnknownFailure"</diagHeader>